Re: [PATCH 3/4] video: add MIPI DBI Type C Option 3 support

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 03.02.22 15:34, Thorsten Scherer wrote:
> Hi Ahmad,
> 
> uups.  I did not see v3 of this patch. Sorry for the noise.

All good. Thanks for looking out :)

> 
> On Wed, Feb 02, 2022 at 10:55:53AM +0100, Ahmad Fatoum wrote:
>> Import the Linux v5.15 state of the driver to allow easy porting of
>> MIPI-DBI displays like the Ilitek 9431 added in a follow-up commit.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> ---
>>  commands/Kconfig         |  23 ++
>>  commands/Makefile        |   1 +
>>  drivers/video/Kconfig    |   3 +
>>  drivers/video/Makefile   |   1 +
>>  drivers/video/mipi_dbi.c | 467 +++++++++++++++++++++++++++++++++++++++
>>  include/spi/spi.h        |  20 ++
>>  6 files changed, 515 insertions(+)
>>  create mode 100644 drivers/video/mipi_dbi.c
>>
>> diff --git a/commands/Kconfig b/commands/Kconfig
>> index ba8ca5cdebce..af60f7be1587 100644
>> --- a/commands/Kconfig
>> +++ b/commands/Kconfig
>> @@ -1969,6 +1969,29 @@ config CMD_SPI
>>  		  -w BIT	bits per word (default 8)
>>  		  -v		verbose
>>  
>> +config CMD_MIPI_DBI
>> +	bool
>> +	depends on DRIVER_VIDEO_MIPI_DBI && SPI
>> +	select PRINTF_HEXSTR
>> +	prompt "mipi_dbi command"
>> +	help
>> +	  write/read from MIPI DBI SPI device
>> +
>> +	  Usage: mipi_dbi [-wld] [REG] [DATA...]
>> +
>> +	  Options:
>> +		  -l		list all MIPI DBI devices
>> +		  -d DEVICE	select specific device (default is first registered)
>> +		  -w		issue write command
>> +
>> +BAREBOX_CMD_START(mipi_dbi)
>> +	.cmd		= do_mipi_dbi,
>> +	BAREBOX_CMD_DESC("write/read from MIPI DBI SPI device")
>> +	BAREBOX_CMD_OPTS("[-wld] [REG] [DATA...]")
>> +	BAREBOX_CMD_GROUP(CMD_GRP_HWMANIP)
>> +	BAREBOX_CMD_HELP(cmd_mipi_dbi_help)
>> +BAREBOX_CMD_END
>> +
>>  config CMD_LED_TRIGGER
>>  	bool
>>  	depends on LED_TRIGGERS
>> diff --git a/commands/Makefile b/commands/Makefile
>> index db78d0b877f6..fffb6d979e82 100644
>> --- a/commands/Makefile
>> +++ b/commands/Makefile
>> @@ -67,6 +67,7 @@ obj-$(CONFIG_CMD_GPIO)		+= gpio.o
>>  obj-$(CONFIG_CMD_UNCOMPRESS)	+= uncompress.o
>>  obj-$(CONFIG_CMD_I2C)		+= i2c.o
>>  obj-$(CONFIG_CMD_SPI)		+= spi.o
>> +obj-$(CONFIG_CMD_MIPI_DBI)	+= mipi_dbi.o
>>  obj-$(CONFIG_CMD_UBI)		+= ubi.o
>>  obj-$(CONFIG_CMD_UBIFORMAT)	+= ubiformat.o
>>  obj-$(CONFIG_CMD_MENU)		+= menu.o
>> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
>> index 1b8672fdea82..70d1d809536b 100644
>> --- a/drivers/video/Kconfig
>> +++ b/drivers/video/Kconfig
>> @@ -129,6 +129,9 @@ config DRIVER_VIDEO_EDID
>>  	  This enabled support for reading and parsing EDID data from an attached
>>  	  monitor.
>>  
>> +config DRIVER_VIDEO_MIPI_DBI
>> +	bool
>> +
>>  config DRIVER_VIDEO_BACKLIGHT
>>  	bool "Add backlight support"
>>  	help
>> diff --git a/drivers/video/Makefile b/drivers/video/Makefile
>> index 7f4429278987..a7b70d82072a 100644
>> --- a/drivers/video/Makefile
>> +++ b/drivers/video/Makefile
>> @@ -9,6 +9,7 @@ obj-$(CONFIG_VIDEO_VPL) += vpl.o
>>  obj-$(CONFIG_DRIVER_VIDEO_MTL017) += mtl017.o
>>  obj-$(CONFIG_DRIVER_VIDEO_TC358767) += tc358767.o
>>  obj-$(CONFIG_DRIVER_VIDEO_SIMPLE_PANEL) += simple-panel.o
>> +obj-$(CONFIG_DRIVER_VIDEO_MIPI_DBI) += mipi_dbi.o
>>  
>>  obj-$(CONFIG_DRIVER_VIDEO_ATMEL) += atmel_lcdfb.o atmel_lcdfb_core.o
>>  obj-$(CONFIG_DRIVER_VIDEO_ATMEL_HLCD) += atmel_hlcdfb.o atmel_lcdfb_core.o
>> diff --git a/drivers/video/mipi_dbi.c b/drivers/video/mipi_dbi.c
>> new file mode 100644
>> index 000000000000..48b1110f72ab
>> --- /dev/null
>> +++ b/drivers/video/mipi_dbi.c
>> @@ -0,0 +1,467 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * MIPI Display Bus Interface (DBI) LCD controller support
>> + *
>> + * Copyright 2016 Noralf Trønnes
>> + */
>> +
>> +#define pr_fmt(fmt) "mipi-dbi: " fmt
>> +
>> +#include <common.h>
>> +#include <linux/kernel.h>
>> +#include <linux/sizes.h>
>> +#include <gpiod.h>
>> +#include <regulator.h>
>> +#include <spi/spi.h>
>> +#include <video/mipi_dbi.h>
>> +
>> +#include <video/vpl.h>
>> +#include <video/mipi_display.h>
>> +#include <video/fourcc.h>
>> +
>> +#define MIPI_DBI_MAX_SPI_READ_SPEED 2000000 /* 2MHz */
>> +
>> +#define DCS_POWER_MODE_DISPLAY			BIT(2)
>> +#define DCS_POWER_MODE_DISPLAY_NORMAL_MODE	BIT(3)
>> +#define DCS_POWER_MODE_SLEEP_MODE		BIT(4)
>> +#define DCS_POWER_MODE_PARTIAL_MODE		BIT(5)
>> +#define DCS_POWER_MODE_IDLE_MODE		BIT(6)
>> +#define DCS_POWER_MODE_RESERVED_MASK		(BIT(0) | BIT(1) | BIT(7))
>> +
>> +LIST_HEAD(mipi_dbi_list);
>> +EXPORT_SYMBOL(mipi_dbi_list);
>> +
>> +/**
>> + * DOC: overview
>> + *
>> + * This library provides helpers for MIPI Display Bus Interface (DBI)
>> + * compatible display controllers.
>> + *
>> + * Many controllers for tiny lcd displays are MIPI compliant and can use this
>> + * library. If a controller uses registers 0x2A and 0x2B to set the area to
>> + * update and uses register 0x2C to write to frame memory, it is most likely
>> + * MIPI compliant.
>> + *
>> + * Only MIPI Type 1 displays are supported since a full frame memory is needed.
>> + *
>> + * There are 3 MIPI DBI implementation types:
>> + *
>> + * A. Motorola 6800 type parallel bus
>> + *
>> + * B. Intel 8080 type parallel bus
>> + *
>> + * C. SPI type with 3 options:
>> + *
>> + *    1. 9-bit with the Data/Command signal as the ninth bit
>> + *    2. Same as above except it's sent as 16 bits
>> + *    3. 8-bit with the Data/Command signal as a separate D/CX pin
>> + *
>> + * Currently barebox mipi_dbi only supports Type C option 3 with
>> + * mipi_dbi_spi_init().
>> + */
>> +
>> +#define MIPI_DBI_DEBUG_COMMAND(cmd, data, len) \
>> +({ \
>> +	if (!len) \
>> +		pr_debug("cmd=%02x\n", cmd); \
>> +	else if (len <= 32) \
>> +		pr_debug("cmd=%02x, par=%*ph\n", cmd, (int)len, data);\
>> +	else \
>> +		pr_debug("cmd=%02x, len=%zu\n", cmd, len); \
>> +})
>> +
>> +static const u8 mipi_dbi_dcs_read_commands[] = {
>> +	MIPI_DCS_GET_DISPLAY_ID,
>> +	MIPI_DCS_GET_RED_CHANNEL,
>> +	MIPI_DCS_GET_GREEN_CHANNEL,
>> +	MIPI_DCS_GET_BLUE_CHANNEL,
>> +	MIPI_DCS_GET_DISPLAY_STATUS,
>> +	MIPI_DCS_GET_POWER_MODE,
>> +	MIPI_DCS_GET_ADDRESS_MODE,
>> +	MIPI_DCS_GET_PIXEL_FORMAT,
>> +	MIPI_DCS_GET_DISPLAY_MODE,
>> +	MIPI_DCS_GET_SIGNAL_MODE,
>> +	MIPI_DCS_GET_DIAGNOSTIC_RESULT,
>> +	MIPI_DCS_READ_MEMORY_START,
>> +	MIPI_DCS_READ_MEMORY_CONTINUE,
>> +	MIPI_DCS_GET_SCANLINE,
>> +	MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
>> +	MIPI_DCS_GET_CONTROL_DISPLAY,
>> +	MIPI_DCS_GET_POWER_SAVE,
>> +	MIPI_DCS_GET_CABC_MIN_BRIGHTNESS,
>> +	MIPI_DCS_READ_DDB_START,
>> +	MIPI_DCS_READ_DDB_CONTINUE,
>> +	0, /* sentinel */
>> +};
>> +
>> +bool mipi_dbi_command_is_read(struct mipi_dbi *dbi, u8 cmd)
>> +{
>> +	unsigned int i;
>> +
>> +	if (!dbi->read_commands)
>> +		return false;
>> +
>> +	for (i = 0; i < 0xff; i++) {
>> +		if (!dbi->read_commands[i])
>> +			return false;
>> +		if (cmd == dbi->read_commands[i])
>> +			return true;
>> +	}
>> +
>> +	return false;
>> +}
>> +
>> +int mipi_dbi_command_read_len(int cmd)
>> +{
>> +	switch (cmd) {
>> +	case MIPI_DCS_READ_MEMORY_START:
>> +	case MIPI_DCS_READ_MEMORY_CONTINUE:
>> +		return 2;
>> +	case MIPI_DCS_GET_DISPLAY_ID:
>> +		return 3;
>> +	case MIPI_DCS_GET_DISPLAY_STATUS:
>> +		return 4;
>> +	default:
>> +		return 1;
>> +	}
>> +}
>> +
>> +/**
>> + * mipi_dbi_command_read - MIPI DCS read command
>> + * @dbi: MIPI DBI structure
>> + * @cmd: Command
>> + * @val: Value read
>> + *
>> + * Send MIPI DCS read command to the controller.
>> + *
>> + * Returns:
>> + * Zero on success, negative error code on failure.
>> + */
>> +int mipi_dbi_command_read(struct mipi_dbi *dbi, u8 cmd, u8 *val)
>> +{
>> +	if (!dbi->read_commands)
>> +		return -EACCES;
>> +
>> +	if (!mipi_dbi_command_is_read(dbi, cmd))
>> +		return -EINVAL;
>> +
>> +	return mipi_dbi_command_buf(dbi, cmd, val, 1);
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_command_read);
>> +
>> +/**
>> + * mipi_dbi_command_buf - MIPI DCS command with parameter(s) in an array
>> + * @dbi: MIPI DBI structure
>> + * @cmd: Command
>> + * @data: Parameter buffer
>> + * @len: Buffer length
>> + *
>> + * Returns:
>> + * Zero on success, negative error code on failure.
>> + */
>> +int mipi_dbi_command_buf(struct mipi_dbi *dbi, u8 cmd, u8 *data, size_t len)
>> +{
>> +	u8 *cmdbuf;
>> +	int ret;
>> +
>> +	/* SPI requires dma-safe buffers */
>> +	cmdbuf = kmemdup(&cmd, 1, GFP_KERNEL);
>> +	if (!cmdbuf)
>> +		return -ENOMEM;
>> +
>> +	ret = dbi->command(dbi, cmdbuf, data, len);
>> +
>> +	kfree(cmdbuf);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_command_buf);
>> +
>> +/* This should only be used by mipi_dbi_command() */
>> +int mipi_dbi_command_stackbuf(struct mipi_dbi *dbi, u8 cmd, const u8 *data,
>> +			      size_t len)
>> +{
>> +	u8 *buf;
>> +	int ret;
>> +
>> +	buf = kmemdup(data, len, GFP_KERNEL);
>> +	if (!buf)
>> +		return -ENOMEM;
>> +
>> +	ret = mipi_dbi_command_buf(dbi, cmd, buf, len);
>> +
>> +	kfree(buf);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_command_stackbuf);
>> +
>> +/**
>> + * mipi_dbi_hw_reset - Hardware reset of controller
>> + * @dbi: MIPI DBI structure
>> + *
>> + * Reset controller if the &mipi_dbi->reset gpio is set.
>> + */
>> +void mipi_dbi_hw_reset(struct mipi_dbi *dbi)
>> +{
>> +	if (!gpio_is_valid(dbi->reset))
>> +		return;
>> +
>> +	gpiod_set_value(dbi->reset, 0);
>> +	udelay(20);
>> +	gpiod_set_value(dbi->reset, 1);
>> +	mdelay(120);
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_hw_reset);
>> +
>> +/**
>> + * mipi_dbi_display_is_on - Check if display is on
>> + * @dbi: MIPI DBI structure
>> + *
>> + * This function checks the Power Mode register (if readable) to see if
>> + * display output is turned on. This can be used to see if the bootloader
>> + * has already turned on the display avoiding flicker when the pipeline is
>> + * enabled.
>> + *
>> + * Returns:
>> + * true if the display can be verified to be on, false otherwise.
>> + */
>> +bool mipi_dbi_display_is_on(struct mipi_dbi *dbi)
>> +{
>> +	u8 val;
>> +
>> +	if (mipi_dbi_command_read(dbi, MIPI_DCS_GET_POWER_MODE, &val))
>> +		return false;
>> +
>> +	val &= ~DCS_POWER_MODE_RESERVED_MASK;
>> +
>> +	/* The poweron/reset value is 08h DCS_POWER_MODE_DISPLAY_NORMAL_MODE */
>> +	if (val != (DCS_POWER_MODE_DISPLAY |
>> +	    DCS_POWER_MODE_DISPLAY_NORMAL_MODE | DCS_POWER_MODE_SLEEP_MODE))
>> +		return false;
>> +
>> +	pr_debug("Display is ON\n");
>> +
>> +	return true;
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_display_is_on);
>> +
>> +#if IS_ENABLED(CONFIG_SPI)
>> +
>> +/**
>> + * mipi_dbi_spi_cmd_max_speed - get the maximum SPI bus speed
>> + * @spi: SPI device
>> + * @len: The transfer buffer length.
>> + *
>> + * Many controllers have a max speed of 10MHz, but can be pushed way beyond
>> + * that. Increase reliability by running pixel data at max speed and the rest
>> + * at 10MHz, preventing transfer glitches from messing up the init settings.
>> + */
>> +u32 mipi_dbi_spi_cmd_max_speed(struct spi_device *spi, size_t len)
>> +{
>> +	if (len > 64)
>> +		return 0; /* use default */
>> +
>> +	return min_t(u32, 10000000, spi->max_speed_hz);
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_spi_cmd_max_speed);
>> +
>> +static bool mipi_dbi_machine_little_endian(void)
>> +{
>> +#if defined(__LITTLE_ENDIAN)
>> +	return true;
>> +#else
>> +	return false;
>> +#endif
>> +}
>> +
>> +/* MIPI DBI Type C Option 3 */
>> +
>> +static int mipi_dbi_typec3_command_read(struct mipi_dbi *dbi, u8 *cmd,
>> +					u8 *data, size_t len)
>> +{
>> +	struct spi_device *spi = dbi->spi;
>> +	u32 speed_hz = min_t(u32, MIPI_DBI_MAX_SPI_READ_SPEED,
>> +			     spi->max_speed_hz / 2);
>> +	struct spi_transfer tr[2] = {
>> +		{
>> +			.speed_hz = speed_hz,
>> +			.tx_buf = cmd,
>> +			.len = 1,
>> +		}, {
>> +			.speed_hz = speed_hz,
>> +			.len = len,
>> +		},
>> +	};
>> +	struct spi_message m;
>> +	u8 *buf;
>> +	int ret;
>> +
>> +	if (!len)
>> +		return -EINVAL;
>> +
>> +	/*
>> +	 * Support non-standard 24-bit and 32-bit Nokia read commands which
>> +	 * start with a dummy clock, so we need to read an extra byte.
>> +	 */
>> +	if (*cmd == MIPI_DCS_GET_DISPLAY_ID ||
>> +	    *cmd == MIPI_DCS_GET_DISPLAY_STATUS) {
>> +		if (!(len == 3 || len == 4))
>> +			return -EINVAL;
>> +
>> +		tr[1].len = len + 1;
>> +	}
>> +
>> +	buf = kmalloc(tr[1].len, GFP_KERNEL);
>> +	if (!buf)
>> +		return -ENOMEM;
>> +
>> +	tr[1].rx_buf = buf;
>> +	gpiod_set_value(dbi->dc, 0);
>> +
>> +	spi_message_init_with_transfers(&m, tr, ARRAY_SIZE(tr));
>> +	ret = spi_sync(spi, &m);
>> +	if (ret)
>> +		goto err_free;
>> +
>> +	if (tr[1].len == len) {
>> +		memcpy(data, buf, len);
>> +	} else {
>> +		unsigned int i;
>> +
>> +		for (i = 0; i < len; i++)
>> +			data[i] = (buf[i] << 1) | (buf[i + 1] >> 7);
>> +	}
>> +
>> +	MIPI_DBI_DEBUG_COMMAND(*cmd, data, len);
>> +
>> +err_free:
>> +	kfree(buf);
>> +
>> +	return ret;
>> +}
>> +
>> +static int mipi_dbi_typec3_command(struct mipi_dbi *dbi, u8 *cmd,
>> +				   u8 *par, size_t num)
>> +{
>> +	struct spi_device *spi = dbi->spi;
>> +	unsigned int bpw = 8;
>> +	u32 speed_hz;
>> +	int ret;
>> +
>> +	if (mipi_dbi_command_is_read(dbi, *cmd))
>> +		return mipi_dbi_typec3_command_read(dbi, cmd, par, num);
>> +
>> +	MIPI_DBI_DEBUG_COMMAND(*cmd, par, num);
>> +
>> +	gpiod_set_value(dbi->dc, 0);
>> +	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
>> +	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
>> +	if (ret || !num)
>> +		return ret;
>> +
>> +	if (*cmd == MIPI_DCS_WRITE_MEMORY_START && !dbi->swap_bytes)
>> +		bpw = 16;
>> +
>> +	gpiod_set_value(dbi->dc, 1);
>> +	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
>> +
>> +	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
>> +}
>> +
>> +/**
>> + * mipi_dbi_spi_init - Initialize MIPI DBI SPI interface
>> + * @spi: SPI device
>> + * @dbi: MIPI DBI structure to initialize
>> + * @dc: D/C gpio
>> + *
>> + * This function sets &mipi_dbi->command, enables &mipi_dbi->read_commands for the
>> + * usual read commands. It should be followed by a call to mipi_dbi_dev_init() or
>> + * a driver-specific init.
>> + *
>> + * Type C Option 3 interface is assumed, Type C Option 1 is not yet supported,
>> + * because barebox has no generic way yet to require a 9-bit SPI transfer
>> + *
>> + * If the SPI master driver doesn't support the necessary bits per word,
>> + * the following transformation is used:
>> + *
>> + * - 9-bit: reorder buffer as 9x 8-bit words, padded with no-op command.
>> + * - 16-bit: if big endian send as 8-bit, if little endian swap bytes
>> + *
>> + * Returns:
>> + * Zero on success, negative error code on failure.
>> + */
>> +int mipi_dbi_spi_init(struct spi_device *spi, struct mipi_dbi *dbi,
>> +		      int dc)
>> +{
>> +	struct device_d *dev = &spi->dev;
>> +
>> +	dbi->spi = spi;
>> +	dbi->read_commands = mipi_dbi_dcs_read_commands;
>> +
>> +	if (!gpio_is_valid(dc)) {
>> +		dev_dbg(dev, "MIPI DBI Type-C 1 unsupported\n");
>> +		return -ENOSYS;
>> +	}
>> +
>> +	dbi->command = mipi_dbi_typec3_command;
>> +	dbi->dc = dc;
>> +	// TODO: can we just force 16 bit?
>> +	if (mipi_dbi_machine_little_endian() && spi->bits_per_word != 16)
>> +		dbi->swap_bytes = true;
>> +
>> +	dev_dbg(dev, "SPI speed: %uMHz\n", spi->max_speed_hz / 1000000);
>> +
>> +	list_add(&dbi->list, &mipi_dbi_list);
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_spi_init);
>> +
>> +/**
>> + * mipi_dbi_spi_transfer - SPI transfer helper
>> + * @spi: SPI device
>> + * @speed_hz: Override speed (optional)
>> + * @bpw: Bits per word
>> + * @buf: Buffer to transfer
>> + * @len: Buffer length
>> + *
>> + * This SPI transfer helper breaks up the transfer of @buf into chunks which
>> + * the SPI controller driver can handle.
>> + *
>> + * Returns:
>> + * Zero on success, negative error code on failure.
>> + */
>> +int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
>> +			  u8 bpw, const void *buf, size_t len)
>> +{
>> +	size_t max_chunk = spi_max_transfer_size(spi);
>> +	struct spi_transfer tr = {
>> +		.bits_per_word = bpw,
>> +		.speed_hz = speed_hz,
>> +	};
>> +	struct spi_message m;
>> +	size_t chunk;
>> +	int ret;
>> +
>> +	spi_message_init_with_transfers(&m, &tr, 1);
>> +
>> +	while (len) {
>> +		chunk = min(len, max_chunk);
>> +
>> +		tr.tx_buf = buf;
>> +		tr.len = chunk;
>> +		buf += chunk;
>> +		len -= chunk;
>> +
>> +		ret = spi_sync(spi, &m);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(mipi_dbi_spi_transfer);
>> +
>> +#endif /* CONFIG_SPI */
>> +
>> +MODULE_LICENSE("GPL");
>> diff --git a/include/spi/spi.h b/include/spi/spi.h
>> index c5ad6bd39ff9..d133e0e21265 100644
>> --- a/include/spi/spi.h
>> +++ b/include/spi/spi.h
>> @@ -409,6 +409,26 @@ spi_message_add_tail(struct spi_transfer *t, struct spi_message *m)
>>  	list_add_tail(&t->transfer_list, &m->transfers);
>>  }
>>  
>> +/**
>> + * spi_message_init_with_transfers - Initialize spi_message and append transfers
>> + * @m: spi_message to be initialized
>> + * @xfers: An array of spi transfers
>> + * @num_xfers: Number of items in the xfer array
>> + *
>> + * This function initializes the given spi_message and adds each spi_transfer in
>> + * the given array to the message.
>> + */
>> +static inline void
>> +spi_message_init_with_transfers(struct spi_message *m,
>> +struct spi_transfer *xfers, unsigned int num_xfers)
>> +{
>> +	unsigned int i;
>> +
>> +	spi_message_init(m);
>> +	for (i = 0; i < num_xfers; ++i)
>> +		spi_message_add_tail(&xfers[i], m);
>> +}
>> +
>>  static inline void
>>  spi_transfer_del(struct spi_transfer *t)
>>  {
>> -- 
>> 2.30.2
>>
>>
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> 
> Best regards
> Thorsten
> 
> --
> Thorsten Scherer | Eckelmann AG | www.eckelmann.de |
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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